A conventional water storage unit includes a plate attached to a side of the water bag and the plate includes multiple chambers along a periphery thereof, the chambers are filled with coolants which are gel-type material with high heat transferring factor. The water bag and the plate are frozen before use and the gel-type coolants are solidified with low temperature. Water is then filled into the water bag and heat is absorbed by the coolants such that the user sucks the water of lower temperature. The water bag is received in a backpack and is connected with a hose so that the user can suck the cool water without dismounting the backpack. However, the water bag and the plate occupy a certain space in the freezer and the solidified coolants take the space that water can be filled in the water bag. The coolants are located on one side of the water bag so that the water close to the other side of the water bag cannot be cooled as the water adjacent the coolants. Furthermore, the chambers are located from the top edge to the lower edge of the water bag so that when part of the water is used, the coolants on the higher position of the water bag do not have any function.
FIG. 9 shows a handle 9 which is cooperated with a sealing rod 83 to seal the opening 81 of the water bag 8, the opening 81 goes around the sealing rod 83 and clamped between the sealing rod 83 and the clamping slot (not shown) of the handle 9. The handle 9 includes a carry hole 91 for convenient carry and two engaging holes 93 with which the hose (not shown) connected to the outlet (not shown) of the water bag 8 is engaged to organize the hose. Three hanging holes 92 are defined through the handle 9 such that the use can hang the handle 9 on a wall (not shown). Although the water bag 8 is equipped with sealing snapping members 82 to seal the opening 81, the sealing snapping members 82 cannot bear pressure and are easily opened.
The present invention intends to provide a water storage unit which includes an outer bag and an inner bag in which a coolant bag is received. The coolant bag is located at the bottom of the water storage unit and the outlet part for the water storage unit is located at the bottom thereof so that the water can be cooled by the coolant in the coolant bag efficiently.